This invention relates to improvement of a heat exchanger which is used for an oil cooler for a vehicle or the like.
Patent Document 1 (Japanese Patent No. 5161709) discloses an oil cooler for a vehicle as a heat exchanger. The oil cooler includes a core, a base plate, and a distance plate. The core includes a plurality of core plates, oil passages (the first medium passage), cooling water passages (the second medium passage), and a vertical passage. The core plates are stacked. The oil passages in which oil (the first medium) flows and the cooling water passages in which cooling water (the second medium) flows are alternately formed in a stacking direction between adjacent core plates. The vertical passage in which oil or cooling water flows is formed along the stacking direction of the core plate. The base plate includes a passage port connected to the vertical passage and is thicker than the core plate. The distance plate is interposed between the base plate and the core, and thicker than the core plate. Furthermore, the distance plate includes a communication passage (bypass passage) which communicates the vertical passage with the passage port. The communication passage is formed through the distance plate.